Congenital abnormalities of the central nervous system are a major cause of prenatal and neonatal mortality and life-long morbidity in surviving infants. A better understanding of normal development will be essential for identifying the causes of these developmental anomalies and for making progress towards their prevention and treatment. While significant advances have been made on morphological aspects of development, relatively little is known about the molecular events which control these processes. Increasing evidence suggests that development depends in large part on the precisely ordered expression and function of a cascade of transcription factors. Alterations in the pattern of expression of these factors in animals leads to significant developmental abnormalities, emphasizing the important role of transcription factors. This proposal focuses on Brain Factor (BF)-1, one of three newly identified transcription factors which are expressed in the brain. They are members of a novel gene family, which we recently discovered, with homology to a Drosophila homeotic gene fork head. Fork head is important in the normal development of the fly. BF-1 expression within the developing mammalian brain is restricted to the telencephalon. Therefore, BF-1 is likely to function in the regional specialization of the brain. Our specific aims are to 1) characterize the structure and function of BF-1. We will determine the three-dimensional structure of the BF-1 DNA binding domain (collaboration) and examine the function of specific amino acids in DNA binding and transcriptional regulation with site-directed mutagenesis. 2) determine how BF-1 gene expression is regulated. We will identify the sequences in the genomic DNA which regulate the cell-specific expression of BF-1 in culture cells and in transgenic mice. The factors which bind to these sequences will then be identified and isolated. 3) examine the function of BF-1 in brain development. In situ hybridization and immunohistochemical methods will be used to analyze BF-1 expression in early development. Mice lacking BF-1 will be generated through gene targeting in embryonic stem (ES) cells to examine the biological role of BF-1.